Mechanism for controlling the admission of air to internal combustion oil engines



Jan. 16, 1934. K, J E. HESSELMAN 1,943,312

MECHANISM FOR CONTROLLING THE ADMISSION OF AIR To INTERNAL COMBUSTION OIL ENGINES Filed NOV. 5, 1929 Patented Jan. 16, 1934 UNITED STATES.

PATENT, OFFICE TION OIL ENGmES Knut Jonas Elias Hesselman, Saltsjo-Storangen, near Stockholm, Sweden Application November 5, 1929, Serial No. 404,913,

and in Sweden November 13, 1928 2 Claims. (01. 123-32) This invention relates to internal combustion oil engines which are provided with regulating means to determine the quantity of fuel oil to be injected for each ignition, In such engines it has been already proposed, in order to promote the combustion, to decrease the supply of air on a reduction of the supply of fuel for each working stroke or ignition by means of a damper or a similar valve inserted in the suction conduit of the engine and mechanically connected to a regulating device of the fuel pump so that the damper is caused to throttle the supply of air as the fuel pump is adjusted under the control of the regulating device to deliver a reduced quantity of fuel oil at each stroke. Such an arrangement, however, gives only an approximate and unreliable regulation of the supply of air, particularly, in case of small quantities of fuel injected for each ignition.

This invention has for its object to provide a simple and reliable air regulating device operating over the entire load range of the engine, especially for such engines having a practically constant number of revolutions, as for instance, engines to drive dynamo electric machines or transmissions as well as for engines in which a given amount of fuel injected always corresponds to a-determined number of revolutions,

as engines to drive propellers in which a reduced amount of fuel injected always corresponds to a number of revolutions reduced according to a given law.

The invention is characterized, chiefly, by the fact that inserted in the air suction conduit of the engine is a throttling device in the shape of a slide valve mechanism controlled by the fuel regulating device in which by a special shape of the operating edge of the slide valve, or by a special shape of the air inlet ports of the mechanism, or by the use of a special cam transmission between the slide and the said regulating device the ratio of the amount of air supplied for each working stroke to the amount of fuel injected for each working stroke is maintained constant or substantially constant.

In the accompanying drawing Fig. 1 is a vertical section of a preferred embodiment of the invention. Fig. 2 shows a development of the operating edge of the slide valve shown in Fig. 1, as adapted for an engine of constant number of revolutions. Fig. 8' shows a similar development in respect of an engine adapted to drive propellers. Figs. 4 and 5 are diagrammatic side elevations of modified embodiments. 55 With reference to Fig. 1 the numeral 1 indicates the cylinder of an internal combustion engine of a type in which a given amount of fuel injected always results in a determined number of revolutions. The injection is effected through the nozzle 2 supplied with fuel from the pump 3. Combined with the fuel pump 3 is a device to control the quantity to be injected, said device comprising, as shown, a lever 5 engaging the pump plunger 4 to limit the suction stroke of the plunger, and a hand lever 6 by means of which the lever 5 may be manually operated, if desired. The suction stroke of the plunger 4 is effected, as shown, by a spring 7, whereas the discharge stroke is effected by a cam 8 through the intermedium of a sliding block 9.

The admission of air to the cylinder takes place through a channel 10 the connection of which with the cylinder is controlled by the valve 11. The connection between the channel 10 and the atmosphere is controlled by a regulating mechanism contained in a casing 12 communicating with the channel 10 and open to the atmosphere at 14. The regulating mechanism comprises a slide valve 13 controlling a row of openings 14 in the casing 12 by means of its upper edge. The slide valve 13 is carried by the stem 15 carrying outside the slide valve casing 12 a loading spring 16 tending .fto maintain the slide valve in full open state. The lower end of the stem 15 rests on the control lever 6 above referred to.

The operation is as follows:

With the engine working at normal or full load the slide valve is in its lowermost position in which the air may-enter freely through the openings 14. At the beginning of the compression period there will thus exist, practically, atmospheric pressure within the cylinder. When the load is reduced and the fuel pump regulating mechanism is, as a result, operated to reduce the quantity of fuel injected, by moving the control lever upwards, the stem 15 with slide 13 will at the same time be lifted. According as the pump stroke is reduced the slide valve will be lifted to throttle the air admission through the openings 14. The upper edge of the slide valve is shaped as a curve, as shown at 17, of such a shape as to secure a throttling corresponding to the pump stroke. In engines operating at practically constant number of revolutions the throttling should take place more slowly, for instance, as indicated by the curve 17 shown in Fig. 2. In engines adapted to drive propellers the throttling should be more rapid, for instance, as indicated by the curve 17 shown in Fig. 3, that is, a given pump stroke shorter than the normal corresponds in such engines to a lower number of revolutions and a smaller air inlet opening at the' slide valve than in engines operating at constant number of revolutions. An adjustable no-load aperture is shown at 18, Fig. 1, to facilitate the regulation and prevent too large reduction of the pressure in case of a pump stroke equal to 0 which according to the rule set forth would result in a cylinder pressure equal to 0. It is evident that pump strokes shorter than those corresponding to noload running are of no practical importance in the types of engines now under consideration.

The same eifect as described above may also be obtained by forming the upper edge of the slide valve 13 straight as shown at 17a, Fig. 4, whereas the air admission opening or openings 14a of the slide valve casing is or are given such a shape at its upper portion as to secure the proportionality between fuel oil and air desired.

A still further method by which to obtain the same result is to use a cam transmission of special design between the fuel pump regulating lever 5 and the stem 15 of the slide valve. In Figs. 4 and 5 such a cam transmission is shown which comprises a longitudinally adjustable rod 20 provided with cams 21, 22 adapted to be engaged by a member 23 connected with the lever 5 and by the slide valve stem 15, respectively.

I have discovered, as will be evident from the foregoing description of devices for accomplishing the principal object of the invention, that is, the maintenance of a given proportion or ratio of air to fuel under varying conditions of partial engine load, that the desired proportionality of air to fuel is not obtained, as might be expected, by means operating to restrict the air opening progressively in a uniform manner upon diminution of the fuel supply. Instead of an arrangement which might be expected to give the desired result, I have found that the desired result is obtained by varying the size of the air opening more or less abruptly and at different rates of variation for different ranges of movement of given value of the fuel regulating means. The proper variations in the rate at which the air opening is altered will vary slightly with different specific engine designs but in general the desired results will be obtained if the edges of the members forming the throttle valve structure are provided with contours of thecharacter herein disclosed and arranged to operate relative to each other in the manner which I have shown.

What I claim is:

1. In an internal combustion oil engine, in combination, a fuel pump, regulating means for governing the quantity of fuel delivered by the pump for each working stroke of the engine, means providing a channel for supplying air to the engine for combustion and throttle valve means for controlling the flow of air through said channel, said throttle valve means comprising a cylindrical casing having peripherally disposed ports for the admission of the main air supply for the engine and a reciprocable piston valve in said casing movable in response to movement of said regulating means, said ports having edges substantially normal to the direction of movement of said valve and said valve having a cooperating edge of curved contour and including a recess extending longitudinally of the valve, said edges and recess providing for closing of saidports at a rate variable with respect to the rate of closing movement of the valve whereby to provide for a substantially constant ratio between the quantities of air and fuel supplied for each working stroke of the engine in the range of low engine loads.

2. In an internal combustion oil engine, in combination, a fuel pump comprising a plunger, regulating means for governing the quantity of fuel delivered by the pump for each working stroke comprising an element adapted to engage the plunger and movable to vary the stroke thereof, means providing a channel for supplying air to the engine for combustion, throttle valve means for governing the flow of air through said channel, said throttle valve means comprising a cylindrical casing having peripherally disposed ports for the admission of the main air supply for the engine and a reciprocable piston valve in said casing, and means operatively connected with said element for causing movement of said valve in accordance with movement of said element, said ports having edges substantially normal to the direction of movement of said valve and said valve having a curved edge including a recess adapted to cooperate with said edges of the ports to cause the area for flow of air through the ports to be diminished at a rate variable with respect to the rate of closing movement of said valve so as to provide a substantially constant ratio between the quantities of air and fuel supplied for each working stroke of the engine in the range of low engine loads.

KNUT JONAS ELIAS HESSELMAN. 

